The human papilloma virus or one of its variants is the known cause of the common wart and probably causes focal epithelial hyperplasias and papillomas of the oral cavity and larynx. Common warts, hyperplasias and papillomas are being examined by light microscopy to confirm the clinical diagnosis and by electron microscopy to identify which individual lesions contain papilloma virions. Papilloma viruses are then extracted from individual lesions, purified and their DNA radioactively labeled as a "probe" for DNA-DNA and DNA-RNA molecular hybridization studies with DNA and RNA extracted from papilloma virus or tumor cells from other lesions. The results obtained from the molecular hybridization studies will determine the degree of relatedness, if any, that exists between the human wart virus and the intact or integrated viruses in the hyperplasias and papillomas.